A parallel plate air capacitor has capacity \(C\) and plate area \(A\). Now the space between its plates is filled by two slabs of thickness \(\frac{d}{2}\) each, having dielectric constants \(K_{1}\) and \(K_{2}\). Distance of separation between plates is \(d\). The capacity of the capacitor is (\(\varepsilon _{0}\) = permittivity of free space)